The Libel Reform Campaign has been battling for fairer libel laws for almost four years. Dozens of organisation have joined the campaign and tens of thousands of grassroots supporters have signed petitions, blogged, written to MPs and attended rallies. This resulted in manifesto pledges from all three parties, and in turn this led to a defamation bill that has gradually made its way through parliament with cross-party support. However, with victory in sight, free speech advocates were hit by a sucker punch delivered by Sir Edward Garnier MP.

Prior to this week's House of Commons debate, Garnier, who is also a libel lawyer, submitted an 11th-hour amendment, which was adopted by the government and has stripped the bill of two of its important elements. First, there was the widely supported measure to stop companies that deliver public services from bullying and gagging their critics. Second, there was a growing consensus that there should be restrictions on the ability of companies to sue for libel by making them demonstrate actual or likely financial harm before trying to silence criticism. Both these proposals, which are very moderate steps, have now been abandoned.

Many of the worst cases that triggered the campaign for libel reform involved corporations suing critics, so these particular sections of the bill are vital to reduce future abuses of libel law. Indeed, I was sued by the British Chiropractic Association after writing an article in the Guardian in 2008. The case cost the two sides a total of approximately £500,000. Although I won the case, the damage done to me and my family was enormous. However, had the BCA been forced to show that my article had caused it serious financial harm, then the action would have been thrown out immediately. This would have saved both me and the BCA a great deal of time, money and stress.

By removing any restrictions on the use of libel laws by corporations, the government is ignoring the advice of the joint scrutiny committee on the draft defamation bill, chaired by Lord Mawhinney, which stated: "It is unacceptable that corporations are able to silence critical reporting by threatening or starting libel claims which they know the publisher cannot afford to defend and where there is no realistic prospect of serious financial loss."

Similarly, in 2010, the House of Commons culture, media and sport select committee recommended that it should be necessary for "a corporation to prove actual damage to its business before an action could be brought".

However, all is not lost. Liberal MPs such as Julian Huppert and Conservative MP Peter Bottomley have pointed out in the strongest terms how libel law has been abused in the past and how this will continue in the future unless the issue of corporations is dealt with in the defamation bill. This reinforces the view of the Labour shadow justice team, who have repeatedly backed the Libel Reform Campaign on the issue of corporations.

In response, Helen Grant, the minister for courts and victims, said the government would "actively consider" amendments to the bill that would require corporations to show financial loss before they can sue for libel. This is vague, but it does leave open the possibility that these elements can be re-introduced into the bill when it heads to the House of Lords next week. The government now has a final opportunity to do the right thing.

When I attended a forum on libel reform at the British Academy in 2011, 20 figures ranging from law professors to leading libel law firm, Carter Ruck, from MPs to free speech groups, discussed the issue of corporations. There was unanimous agreement that there needed to be restrictions on the right of corporations to sue in libel.

Even corporations are not arguing against this moderate restriction to their ability to silence critics. Almost the only person who seems to be particularly keen to encourage companies to sue bloggers, scientists, Mumsnet, Which? and human rights groups is Sir Edward Garnier. I hope that the government will ignore him.